This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. One of the most powerful tools for analyzing ion channel structure/function has been the identification of natural toxins agonists and antagonists. Several organisms produce small protein toxins that act on ion channels and aid in prey capture or defense. We propose to study toxin interaction with the ion channel TRPV1. We will use MALDI mass spectrometry to assess the molecular composition of toxins isolated by reverse phase chromatography. The UCSF Mass Spectrometry Facility will assist in the collection to determine the molecular weight of isolated toxins.